A prominent leader of a group with al Qaeda links died while being held by a Lebanese jail Saturday.

The Lebanese army said in a statement that Majid al-Majid “died this morning while undergoing treatment at the central military hospital after his health deteriorated,” the Associated Press reports.

The cause of al-Majid’s death is unclear, but an anonymous Lebanese army general told the AP he suffered from kidney failure. State-run National News Agency also said he died “after his health conditions deteriorated.”

The alleged commander of the Abdullah Azzam Brigades was detained in Lebanon last month while on his way from Beirut to the Bekaa Valley, which borders Syria. Abdullah Azzam Brigades, an al Qaeda-linked Sunni militant group, is behind attacks throughout the Middle East and into Syria.

Al-Majid is considered one of the 85 most-wanted men in home country of Saudi Arabia. His brigades claimed November’s Iranian Embassy bombing in Beirut that killed more than 20 people.